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Cool Nights Coming

August 3, 2013 10:44 AM

A narrow swath of showers and thunderstorms raced eastward across MA last evening. Some areas received nothing more than a quick burst of brisk winds and a few sprinkles while some spots north of Boston got briefly drenched with some nasty cloud to ground lightning bolts. That action was triggered by the first of three impulses riding through the jet stream and providing energy to the atmosphere. The next perturbation arrives today but it is weaker and not likely to deliver any deluge. A parcel of rain is streaming out across southern CT early this morning and there is just a chance that a few renegade sprinkles or light showers could visit RI or southeastern MA. Coincidentally, another bundle of rain is moving swiftly from the northern half of NH into ME this morning. In the wake of these departing drops, the cloudiness will thin out and shift southeastward in waves leading to times of brighter sunshine. As the minor impulse and weak frontal boundary cross southern New England later this afternoon and early evening, there could be a broken belt of showers and isolated lightning mainly near and south of the MA Pike. Therefore, thankfully, everyone involved in the Pan Mass Challenge will probably have a dry day as the bike-a-thon progresses from Sturbridge to Provincetown in more comfortable conditions than those of last year. GOOD LUCK to one and all! Expect high temperatures of 81-85 today with a westerly wind freshening to 10-20 mph and decreasing humidity along and south of the MA Pike.

It will become mostly clear tonight so the viewing will be ideal for the fabulous fireworks show starting at 9:15 pm in Newburyport in celebration of its Yankee Homecoming Days which concludes tomorrow. The air will be nice and dry with overnight lows in the middle 50s to middle 60s across the region. The final short wave and frontal boundary will approach tomorrow so the day will start with bright sunshine. A more unstable environment will set up during the day resulting in more and more developing and building clouds. Some of them will tower into showers and thunderstorms that will track southeastward from northern New England and cross into MA as the afternoon moves on. Little, if any, action will show up over southeastern MA and Cape Cod until late afternoon. Temperatures will have an opportunity to close in on the 80-degree mark before the showers commence. Once the boundary passes, cooler and even drier air will invade the region for Monday into Wednesday. This will enable everyone to open up their homes to the flow of fresh dry air to scour out the staleness. In fact, the suburban overnight lows in the lower 50s tomorrow night and the upper 40 on Monday night will force some sleepers to reach for a blanket! The beginning of the work week will feature ample sunshine so a warmup to the middle to upper 70s will occur making for some great weather for outside work and sports activities from the mountaintops to the seashore. High tides over the next few days will happen during the late mornings with low tides in the late afternoons. The westerly wind will be brisk on Monday but be light and variable in direction leading to a sea breeze at the coast on Tuesday.

Looking ahead, shifting steering currents will cause a thrust of warm, muggy air to advance toward New England late Wednesday. This push will produce a ribbon of rain and embedded boomers on Thursday as the warm frontal boundary chugs in with more showers and thunderstorms generated on Friday as the cold frontal boundary tracks eastward into the region. Present indications suggest no substantial clearing behind the warm front so a spike to 90 degrees or more seems unlikely currently. Hopefully, that will reduce the risk of an outbreak of severe weather on Friday. In any event, breezy, cooler and drier air will return next weekend.

Joe Joyce will post an updated blog this evening and I shall return early Monday morning.